An 88-year-old male had progressive painful skin lesions on his left upper arm for 3 months. His medical history included hypertension, hyperlipidemia, chronic kidney disease, and coronary artery disease. Physical examinations revealed the multiple indurated erythematous nodules and plaque limited to his left upper arm [Figure 1]. There was no lymphadenopathy on both axillary and clavicular areas. He denied other systemic symptoms, including fever, body weight loss, night sweating, and changes in bowel habits. Based on suspicion of cutaneous metastasis, skin biopsy was performed.

Figure 1: Clinical presentation. Multiple erythematous indurated nodules and coalescing plaques on the left upper arm of the 88-year-old man

The pathology showed dense dermal infiltration of mononuclear cells that extended into the subcutis, without the involvement of the epidermis [Figure 2]a. The tumor cells were large, atypical lymphoid cells resembling immunoblasts and plasmacytoid cells, [Figure 2]b and they were diffusely positive for CD138 immunohistochemically [Figure 2]c, with high expression of Ki-67. They were negative for CD3, CD20, CD30, ALK, and CD4. Lambda and kappa staining showed lambda light chain restriction. The tumor cells also showed high nuclear expression for the Epstein–Barr virus-encoded small RNAs [Figure 2]d. A diagnosis of plasmablastic lymphoma (PBL) was made.

The tests for the human immunodeficiency virus (HIV) infection and other immunosuppressive disorders were negative. The complete blood cell count was normal. Lactic dehydrogenase (215 IU/L, normal range: 98–192 IU/L) and β2-microglobulin (3971 ng/mL, normal range: 609–2366 ng/mL) levels were elevated. Computed tomography (CT) for the chest and abdomen and bone marrow study did not show an internal organ involvement.

The oncologist administered 50 mg/day of cyclophosphamide and concurrent radiotherapy of 1800 cGy, with each fraction of 200 cGy for nine fractions. After a few courses of radiotherapy, the patient experienced a pathologic fracture of his left humerus without violent trauma. Surgical fixation was performed. The bony tissue showed the involvement of PBL.

Radiography of his left upper arm was not performed before the therapy. Therefore, it was difficult to evaluate the bony involvement occurred before or after the cutaneous PBL. The staging turned into the Ann Arbor Stage IV. The patient refused to complete either radiotherapy or chemotherapy. Multiple bone and soft-tissue metastasis occurred subsequently. The patient died after a surviving for 16 months.

PBL is a rare disease that is strongly associated with immunocompromised conditions. More than 70% of patients had an HIV infection.[1] The primary skin presentation was rare and reported in approximately 7% of cases.[2] There are two peak ages, namely, the younger group (mean age, 39 years) in HIV-positive patients and the older group (mean age, 58 years) in HIV-negative patients. The male-to-female ratio is around 4:1–5.7:1.[1]

In a recently reported series, the immune status in PBL patients can be classified as HIV-positive, posttransplantation, and HIV-negative/nontransplanted.[3] The HIV-negative/nontransplanted group might have had underlying autoimmune disorders, systemic inflammatory diseases, or localized current inflammation.[3] Approximately, 23% (31/135) of patients were older than 60 years but did not have any underlying diseases.[3]

The clinical presentation in HIV-negative patients with PBL predominantly occurs in extranodal sites, such as the oral cavity, nasal cavity, and gastrointestinal tract.[4] Skin involvement is only found in 6.7% of patients. Many patients have an advanced stage (stage IV in 44.4%) when diagnosed; thus, it is difficult to identify the primary site.[4] Positron-emission tomography (PET)/CT may provide great help in the staging and prediction of the outcome.[5] Unfortunately, PET was not available in the remote branch hospital and was not performed in this patient.

The diagnosis of PBL is based on pathology. A panel of immunohistochemistry examinations for B-lymphocytes, plasma cells, and myeloid cells areoften needed. In general, the tumor cells of PBL are positive for VS38c, CD38, multiple myeloma oncogene-1, CD138, and express a high-proliferation index, such as Ki-67 (usually >80%).[6],[7]

Viruses play an important role in the occurrence of PBL, especially HIV and the Epstein–Barr virus (EBV).[1] Dual infection is commonly found.[1] The prevalence of EBV infection in PBL was higher in HIV-positive patients (72%) than in HIV-negative patients (58.4%).[3],[4] Our patient also showed high expression of EBER in the tumor cells. However, the role of EBV infection was not fully understood.

It is interesting that the overall survival rate is better in HIV-positive patients than in HIV-negative patients, with a survival rate of 14 months and 9 months, respectively.[1],[3] It was even worse in a Chinese study, where 60 HIV-negative patients with PBL had a median overall survival of 7 months.[8] The presence of EBER has been revealed to have a better outcome in France.[3] There was no prognostic influence in Chinese study.[8] Therefore, there may be a racial difference among different populations.

In conclusion, we report a rare case of PBL that initially had cutaneous presentation, followed by the bony involvement. The initial staging investigation should be more comprehensive.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.